The aim of this study was to determine whether gluten ingestion can induce gastrointestinal symptoms in non-celiac individuals. A double-blind, randomized, placebo-controlled rechallenge trial was undertaken in patients with irritable bowel syndrome in whom celiac disease was excluded and who were symptomatically controlled on a gluten-free diet. The study included 34 patients (aged 29-59 years) who received either (i) gluten or (ii) placebo in the form of two bread slices plus one muffin per day with a gluten-free diet for up to 6 weeks.

The study found:
(a) 28% more of the patients in the gluten group reported that their symptoms were not adequately controlled compared to the placebo group.
(b) Patients in the gluten group were significantly worse within one week for the following:
(i) Overall symptoms.
(ii) Pain.
(iii) Bloating.
(iv) Less satisfaction with stool consistency.
(v) Tiredness.

The results from the study suggests that a diet containing gluten causes gastrointestinal symptoms in non-celiacs.